I remember this game. It was bad. But the worst? I dunno, can you name video games that are worserer?
ET gets a bad rap for starting the videogame crash in the 80s, but no, I would say in terms of actual content, it was not the worst game in history. Superman 64, as mentioned, is a horrendous monster of a game. And there are also games that are overly sexist, or this new onset of Free-to-Play, Pay-to-Win garbage games on smartphones and the like.
Looking for Big Rigs, found this: top 10 weirdest racing games
http://jalopnik.com/the-ten-weirdest-car-video-games-504388733 Big Rigs is #10. I watched #9 and it was actually worth watching. It gets really really weird.
Oh! Desert Bus! That was the other one I was trying to think of. Where you just drive back and forth between Tucson and Vegas in real time over and over again. That is easily the worst video game ever created, I think. I just can't think of a metric where it's not. insomniasexx agrees with me.
This guy has instructions to 'fix' E.T. for the Atari 2600 by modifying the binary to fix bugs and inconveniences and even E.T's color.It turns out that E.T. isn't a bad game after all. With a few simple changes we were able to dramatically improve an already good game